Astronomers have discovered a new solar system 127 light years away that is tantalisingly similar to our own.

The team used observations from the European Southern Observatory (Eso) in Chile to find five Neptune-like planets orbiting a Sun-like star called HD 10180. The planets are closer to their star than Mars is to the Sun.

They also have some evidence that two more planets might be in the star system, one of which would have the lowest mass of any extrasolar planet ever found. If the existence of these two additional planets is confirmed, the discoveries would make the HD 10180 solar system very similar to our own, with seven planets (to our eight) and a regular pattern of orbits.

"We have found what is most likely the system with the most planets yet discovered," said Christophe Lovis of the University of Geneva in Switzerland. "This remarkable discovery also highlights the fact that we are now entering a new era in exoplanet research: the study of complex planetary systems and not just of individual planets. Studies of planetary motions in the new system reveal complex gravitational interactions between the planets and give us insights into the long-term evolution of the system."

One of the two as-yet-unconfirmed planets is likely to be similar to Saturn, with a minimum mass of around 65 Earths and an orbit of 2,200 days. The other planet would be the least massive exoplanet ever discovered, say astronomers, with a mass around 1.4 times that of the Earth.

The similarities end there, however. The rocky planet is likely to orbit very close to its star – just 2% of the distance between the Earth and the Sun. A single "year" on this planet would last only 1.18 Earth days.

Scientists have confirmed the existence of 15 "extrasolar systems" that have at least three planets and the previous record-holder was 55 Cancri, which has five planets in orbit around it.

The latest discovery was announced today at an international meeting at the Observatoire de Haute-Provence in France.

Lovis and his team used six years of measurements from the Harps spectrograph at Eso's 3.6m telescope in La Silla, Chile, to scrutinise the Sun-like star HD 10180, which is in the southern constellation of Hydrus. Astronomers can detect the tiny gravity-induced wobbles in the position of stars that have planets orbiting them.

Damien Ségransan, who worked on the project with Lovis, said that the mystery rocky planet caused a wobble in the star's motion "of only about 3 km/hour – slower than walking speed – and this motion is very hard to measure".